Ask The Science Experts

Hubble’s Constant is the rate ratio of the speed at which a galaxy is moving away from Earth divided by its distance from Earth. Note, this is obviously not our galaxy, but other galaxies in the Universe.

Most scientists estimate the time between the Big Bang and current day somewhere between 13 and 20 billion years ago. Estimates are derived from Hubble’s Constant, a rate of expansion ratio calculated by dividing the speed at which a galaxy is moving away from the Earth by it’s distance from the Earth. Read the rest of this entry »

The half-life of a substance is the time it takes for the number of radioactive nuclei to decrease to one half of the original number. The halflife of a given isotope is always the same, meaning it doesn’t matter how many you have at any given time. Read the rest of this entry »

The phenomenon that explains the apparent change in wavelength of radiation (either sound waves or light waves) due to relative motion between the source and the receiver. This was first described, and hence named after, the Austrian physicist Christian Doppler in 1842. In simpler terms… Read the rest of this entry »

The dimples reduce drag allowing the ball to travel faster for a longer time- and thus farther. The dimples reduce drag because the fast-moving air tends to remain closer to the dimpled surface than it would on a smooth surface. Basically this reduces the eddies and the wake effect. Read the rest of this entry »

One way would be for two people communicating wirelessly to start in a wide-open area and start walking until they could no longer see each other. Of course this is ridiculous. The way it’s usually done, by airports and such, is by looking at predetermined landmarks of known distances. Daytime visibility is defined as the distance in which is is possible to see and identify, with the naked eye, “a prominent dark object against the sky at the horizon.” Read the rest of this entry »

Note, the following is the full article from Atomic Elephant Toy but it contains a decent description of the physics behind this classic toy. You can see more of their science kits and educational toys online. Begin article…

For centuries, students and inventors alike have been intrigued by the idea of a perpetual motion machine. Alas, the second law of thermodynamics has held up to the test of time. It can be written in several forms but Rudolf Clausius may have said it best for our purposes: in an isolated system, a process will only occur if it increases the total entropy of the system. In other words, heat will not naturally flow from a body of lower temperature to one of higher. It will however, flow in the other direction.

So what does all this have to do with our classic drinking bird? The answer: plenty. Couple this law of thermodynamics with Boyle’s law stating the inversely proportional relationship of temperature and pressure relating to volume and you can begin to understand how this magical little bird can seemingly bob up and down forever. Read the rest of this entry »